*3.3. Spatial Conflict of PLES*

The space conflict composite index values (*SCCI*) of the 29 tertiary water resource divisions in the Yellow River Basin were calculated in 2010, 2015, 2018, and 2025 (Table 6), respectively, based on the *SCCI* calculation method. According to the statistical distribution characteristics of the *SCCI*, the *SCCI* values were standardized and then classified into four levels: stably controllable, basically controllable, basically out of control, and seriously out of control. The specific division intervals are as follows: level 1: "stably controllable" [0.00, 0.30); level 2: "basically controllable" [0.30, 0.70); level 3: "basically out of control" [0.70, 0.90); and level 4: "seriously out of control" [0.90, 1.00].

**Table 6.** *SCCI* of the tertiary water resource division from 2010 to 2025.


In 2010, the Loess Plateau area of the middle reaches of the Yellow River showed a severe spatial conflict of PLES in the Yellow River Basin (Figure 6). In this area, the conflict levels in the region of Hekou Town to the left bank of Longmen and the region above Jing River Zhangjiashan were level 4, indicating that the region was seriously out of control; the spatial conflict of PLES level in the Fen River Basin area was level 3, which was within basically out-of-control status; most other areas in the Loess Plateau were considered level 2, meaning that the spatial conflict of PLES was basically controllable. In comparison, the spatial conflicts of PLES in most of the other basin regions such as the lower reaches of the Yellow River, the Ningxia plain, the Inner Mongolia irrigation area, the inland flow area, the Hehuang area, and the source region of the Yellow River were relatively mild and in a stably controllable state of level 1.

**Figure 6.** Spatial conflict of PLES in the Yellow River Basin in 2010.

The spatial distribution of spatial conflict of PLES in the Yellow River Basin in 2015 (Figure 7) was basically the same as that in 2010, and the out-of-control regions, the ones measured as level 3 and level 4, which were located in the middle reaches of the Yellow River Loess Plateau area, still had not been improved, while the spatial conflict of PLES in the region from Heyuan to Maqu area had deteriorated from the stably controllable level 1 to the basically controllable level 2.

In 2018, the spatial conflict of the PLES situation in the Yellow River Basin (Figure 8) improved—only the region from Hekou Town to the left bank of Longmen remained at level 4, indicating a seriously out-of-control status. The region above Jing River Zhangjiashan changed from level 4 to level 3 status, the region Fen River improved from level 3 to level 2 status, and the region from Heyuan to Maqu was at that point at level 1 instead of level 2. Only spatial conflict of PLES of the region Dawen River deteriorated from level 1 to level 2, and the other areas were relatively stable.

**Figure 7.** Spatial conflict of PLES in the Yellow River Basin in 2015.

**Figure 8.** Spatial conflict of PLES in the Yellow River Basin in 2018.

As is shown in the simulation results of spatial conflict of PLES in the Yellow River Basin in 2025 (Figure 9), the spatial conflict of PLES in the Yellow River Basin will continue to improve, and the situation in the Loess Plateau and most of the lower reaches will be in a level 1 or level 2 controllable state. However, the spatial conflict of PLES in the upper reaches of the Yellow River is deteriorating: the conflict level of the Daxia River and Tahoe River region has risen to the seriously out-of-control state of level 4, and the source region of the Yellow River shows different degrees of deterioration, from level 1 to the basically controllable state of level 2.

**Figure 9.** Predicted spatial conflict of PLES in the Yellow River Basin in 2025.

As can be seen from Figure 10, from 2010 to 2025, the spatial conflict of PLES in the Yellow River Basin is in the basically controllable level 1. Among the 29 tertiary water resource divisions, except for the regions of Daxia River and Tao River, above Jing River Zhangjiashan, Hekou Town to the left bank of Longmen, and Fen River, the *SCCI* values are in a stable and controllable state. From the development trend of spatial conflict of PLES in the Yellow River Basin, from 2010 to 2025, 15 of the 29 tertiary water resource divisions in the Yellow River Basin show a significantly decreasing trend of *SCCI*, with a percentage of more than 51%. There are eight regions where spatial conflict of PLES fluctuates (decreasing and then increasing or increasing and then decreasing), accounting for about 28%. At the same time, there are six regions in the basin where spatial conflict of PLES reveals a gradually strengthening trend, accounting for 21%.

**Figure 10.** PLES spatial conflict changes in 29 tertiary water resource divisions from 2010 to 2025.

#### **4. Discussion**

The analysis of the spatio-temporal changes in PLES in the Yellow River Basin from 2010 to 2025 indicates that the urbanization process in the basin has further intensified—the LPS area has further increased, and metropolitan areas with a certain scale have gradually formed around provincial capital cities with population and economic siphoning effects, such as Jinan, Zhengzhou, Xi'an, Taiyuan, Hohhot, Yinchuan, and Lanzhou. In addition, the development of energy and mining industries in the Yellow River Basin continues to be the pillar industries supporting industrial and economic development, and therefore, their areas basically remain stable. The Yellow River Basin still has a pivotal and important role in securing China's energy and mineral resources. The area of PES is still unchanged, compared with 2010. PES is distributed more concentrated in the Loess Plateau of the middle reaches and the upper reaches of the Yellow River, which proves that the construction of concentrated contiguous high-standard farmland for modern agricultural development has achieved its initial results. The EPS in the Yellow River Basin is basically stable, but the EPS connectivity and agglomeration degree increased significantly. The unobstructed degree of biological habitat was strongly guaranteed, so an imminent increase in biodiversity of the basin could be expected. Saline and desertified land management in the upper reaches of the Yellow River Basin and parts of the Loess Plateau continues to be effective, as their total areas continued to decrease, resulting in a slight decrease in ES in the basin. At the same time, owing to the positive impact of the implementation of China's nature reserve policy, the disturbance of ES in the upper Yellow River Basin will be significantly reduced by people's work and living activities, and the ES area will increase significantly. As a result, large areas with national representative natural ecosystem values will be effectively protected.

Judging from the seriousness of spatial conflict of PLES, the encroachment of LPS on other PLES is the most prominent in the Yellow River Basin. With the urbanization of the basin and the strengthening of energy and mineral resources development, the encroachment of LPS on other types of PLES is increasing, which is mainly reflected in the encroachment of PES, EPS, and ES around the periphery of urban development zones and townships, and the phenomenon of "pie spreading" caused by the excessive and disorderly development of towns. The development of energy and chemical bases encroaches on regional EPS and ES, giving rise to regional pasture degradation, soil erosion, land desertification, and soil pollution. This is seen mostly in the regions from Hekou Town to the left bank of Longmen, Fen River, and Shizuishan to the south bank of Hekou Town. In addition, LPS encroachment on EPS and ES in the upper reaches of the Yellow River Basin mainly manifested as the encroachment of urban development, overgrazing, water conservancy, transportation facilities construction, etc. on the plateau grassland meadow, wetlands, and other natural water space, resulting in degradation of grassland meadow and peat swamp wetland and other ecological impacts, concentrated in the area of Daxia and Tao River and other areas.

As revealed from the area of spatial conflict of PLES, the spatial conflict of PLES in the Yellow River Basin mainly focuses on the conflict between PES and EPS, specifically the conversion of land-use types between grassland and cropland. In space, the PES and EPS change areas are highly spatially coordinated. On the one hand, the Ningmeng irrigation area, the Fenwei basin, and the lower Yellow River plain are the main agricultural production regions in China, responsible for the mission of ensuring national food security. The continuous expansion of arable land has inevitably caused encroachment on EPS, especially in some ecologically fragile areas of the Loess Plateau where water and soil resources do not align with each other. Excessive agricultural cultivation has caused the destruction of surface vegetation, increased soil erosion, and deterioration of ecosystem services. In recent years, owing to the continuous promotion of the national project of returning farmland to forest and high standard farmland construction, the original arable land with unsuitable water resources carrying capacity or mismatched soil and water conditions has been gradually withdrawn. Thus, the level of agricultural modernization has continuously increased, alleviating the problem of PES encroachment on EPS to some extent. On the other hand, in recent years, with the overlapping impacts of industrial transformation, population migration, agricultural price fluctuations, etc., the Loess Plateau and other areas that used to be agriculturally dominated regions have lost a large number of their rural population. The phenomenon of abandonment of arable land is very common, resulting in the loss of a large amount of suitable arable land, which formed the passive encroachment of EPS on PES, especially in the region above Jing River Zhangjiashan.

From the perspective of the research scale, there have been few studies on spatial conflicts of PLES in the Yellow River Basin, which mainly focus on administrative units such as urban agglomerations, provinces, and cities [65–67]. However, this study adopted tertiary water resource divisions as the basic research unit to analyze the distribution characteristics of spatial conflicts of PLES, thus enriching the scales of research related to the Yellow River Basin. At the same time, the CA–Markov model was used to simulate the spatial pattern of conflicts, which is highly practical for policymakers to formulate corresponding land-use optimization plans. In terms of research methods, GIS and RS technology are the main means to monitor land-use changes by using raster and vector data [68,69]. In this study, land-use change in the Yellow River Basin was analyzed using classified raster data. Compared with other studies [70–72], this method, based on landscape ecology, obtained good credibility, since it focused on revealing the spatio-temporal evolution of PLES conflicts from the perspective of spatial morphological changes by using relatively few volumes of data.

Water resources are the core resource elements for socio-economic development and ecological protection since the ecosystem service functions such as water connotation, soil conservation, sand fixation, and flood regulation are closely related to water resources. Therefore, this study took the 29 tertiary water resource divisions in the Yellow River Basin as the basic research unit. Moreover, in this research, analyses of PLES patterns and internal mechanisms were carried out, considering the distribution of administrative regions, topography, national economic development, watershed size, and maintaining the unity, combination, and integrity of administrative regions and basin zoning. To analyze the crux of ecological protection and high-quality economic and social development in the Yellow River Basin effectively, the study approach was to examine the coupling relationship

between man and land system, based on the internal mechanism of spatial conflict of PLES. Meanwhile, other factors, including the laws of physical geography and socio-economic development, the carrying capacity of resources and environment, the rigid constraint of ecological protection on water resources and high-quality development of the Basin, and the administrative requirements of regional ecological protection and socio-economic construction, were also considered.

Due to climatic challenges, the changes in land use in the Yellow River Basin had more profound impacts on the surface water cycle now. In recent years, the climate in the Loess Plateau area of the middle reaches of the Yellow River Basin has become warmer and drier. Furthermore, a decrease in atmospheric precipitation recharge and an increase in terrestrial evapotranspiration have led to a decrease in available land serving as water resources. Meanwhile, the Chinese government has implemented a large-scale greening action in the Loess Plateau region [73], increasing the conversion from PES to EPS. Large-scale afforestation improves the regional ecological environment, but also changes the underlying surface structure of the region, affects the local water cycle process, and decreases the gradual surface runoff. According to relevant studies [74], due to the impact of climate change and human activities, the carrying capacity of water resources in the Loess Plateau has been on the verge of overload. At the same time, land-use change in the Yellow River Basin will also affect the local climate by changing the carbon cycle.

There is a large amount of unused land (ES) in the upper reaches of the Yellow River. In the future, following the principle of not affecting the ecological environment, these types of unused land can be fully utilized for the development of renewable energy, including wind, solar, and biomass. Firstly, it can reduce the occupation of limited construction and cultivated land resources in socio-economic development, and lower the conflict between ES, PES, and LPS, and secondly, it will reduce the dependence on fossil fuels to promote carbon neutrality, thus mitigating the adverse effects of climate change.

The spatial conflict of PLES resonates with the game process of ecological protection and socio-economic development in the process of territorial space development and utilization. The macroscopic natural geographical background conditions lay the geographical foundation for the construction of the spatial development and protection pattern of the Yellow River Basin, while socio-economic development, urbanization and industrialization processes, exploitation of mineral resources, and other human activities are the key driving force behind the spatial pattern of land space, accelerating the process of change in spatial patterns of the Yellow River Basin. The ecological conditions in Yellow River Basin are fragile, manifested in its serious shortage of water resources, ecologically sensitive areas and fragile areas, and massive pressure on ecological protection under climate change conditions. Meanwhile, in the process of rapid socio-economic development, disordered and uncontrolled urbanization, industrialization, and exploitation activities of mineral resources have caused a disproportionate spatial pattern of PLES and deterioration in the quality of the ecological environment. Therefore, it is of great practical significance to understand the spatio-temporal pattern of PLES in the Yellow River Basin and identify the characteristics of spatial conflict of PLES scientifically. In this way, the PLES layout of the Yellow River Basin, the efficiency of PLES comprehensive utilization, and the PLES service function will be collectively improved, which eventually will assist in achieving the strategic goals of ecological protection and high-quality development in the Yellow River Basin.
